This invention relates to mosaic infrared sensors and in particular to the adaptation of devices of that type to use in such applications as the direct transmission of time dependent two-dimensional infrared images with real time video reception, the nonscanning tracking of infrared emitting objects, and thermal imaging (nondestructive testing).
In the past various devices such as electron beam readout (VIDICON), charge coupled devices (CCD), charge injection devices (CID) and spaced lead conventional arrays have been used for these purposes. For some applications and particularly as adapted for infrared, however, these prior devices have been found wanting in certain respects. For instance, the first three devices have either a low dynamic range or any generally DC coupled in their readout while spaced lead conventional arrays have blind spots and are generally low resolution devices.
THESE LIMITATIONS CAN BE OVERCOME BY THE USE OF TWO-DIMENSIONAL MOSAIC INFRARED SENSING DEVICES OF THE TYPE DESCRIBED HERE. State-of-the-art fabrication techniques such as electron beam lithography and laser machining permit the ready manufacture of single crystal photoconductive and photovoltaic detectors. One-dimensional multielement mosaics can be produced by these methods having fabrication and wiring blind areas less than 1 percent of the active area. The direct readout capabilities and the single element dimensions in the milli-inch region characteristic of these cells allow high responsivity and resolution with low noise.
However, the principal difficulty encountered in the fabrication of direct readout two-dimensional arrays using these devices is the problem of providing electrical connections to each photoconductive or photovoltaic detector in the array without causing unacceptably large blind spots.
Current technology is capable of manufacturing and wiring a linear or column array of ten detectors with acceptable interdetector spacings (regarding blind spots). These sub-arrays can be further combined to produce larger linear or column arrays with detectors numbering several hundred to as much as several thousand. To date, however, two-dimensional device of this type have not been developed due to blind spots resulting from electrical connections between adjacent columns. The present invention is directed toward solving this problem.